Zitat:
The device is shipped with CKSEL = “0100”, SUT = “10”, and CKDIV8 programmed.
The default clock source setting is the Internal RC Oscillator with longest start-up time
and an initial system clock prescaling of 8. This default setting ensures that all users can
make their desired clock source setting using an In-System or Parallel programmer.
Wobei CKSEL = “0100” eben "Calibrated internal RC Oscillator 8MHz" bedeutet und zusammen mit dem aktivierten "clock prescaling of 8" dein Tiny wohl mit 1MHz rennt.